Habitual Smoking and Perinatal Outcomes in Japan

Introduction: Smoking during pregnancy has been reported to increase the perinatal risk. We investigated the perinatal outcomes in Japanese pregnant women with habitual smoking at pre-pregnancy and during pregnancy who delivered at our institute in Japan. Methods: We reviewed the obstetric records of 9280 Japanese women with singleton delivery at ≥22 weeks of gestation at our institute between 2014 and 2019. On admission for delivery, a routine face-to-face interview was conducted by our midwives to ask about smoking during pregnancy. Results: Of the total 9280 pregnant Japanese women, 532 (5.7%) had smoked before pregnancy. Of these, 272 (51.5%) quitted smoking after being diagnosed with pregnancy, while 258 (49.5%) continued to smoke during pregnancy and were diagnosed with habitual smoking during pregnancy. There was no significant relation between habitual smoking at pre-pregnancy and the perinatal adverse outcomes. However, habitual smoking during pregnancy was associated with the adverse perinatal outcomes such as the increased incidence of placental abruption (adjusted odds ratio [OR] 2.38, p = 0.04) and light-for-gestational-age neonate (adjusted OR 1.72, p = 0.03) on multiple logistic regression analyses. Conclusion: In this study, smoking was found to be associated with the adverse perinatal outcomes. The current results support the importance of smoking cessation during pregnancy.